Any discussion of documents, acts, materials, devices, articles and the like in this specification is included solely for the purpose of providing a context for the present invention. It is not suggested or represented that any of these matters formed part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed in Australia or elsewhere before the priority date of each claim of this application.
It is common for different closures to be driveable by a common type of operator unit, so that a dedicated operator unit is not required for each different type and size of closure. For example, overhead garage doors fall into a number of different types, including sectional doors, overhead curtain doors, and one-piece tilt-up doors (jamb ‘J-type’ or track ‘T-type’, depending on the mechanism). Each different door employs a different guiding mechanism for raising and lowering, and thus exhibits a different movement profile. To couple a common operator unit to different door types can cause problems with regard to safe and effective operation under all conditions.
Safe and effective operation generally involves the following considerations:                (a) the travel speed of the bottom edge of the door is slow enough to ensure that the operator unit has sufficient time to detect the door striking an obstruction, so that the unit may take appropriate action (stopping or reversing) before damage or injury can occur;        (b) the travel speed is fast enough to complete open and close movements within a reasonable time;        (c) the travel speed is slow enough to ensure that the operator unit's coupling to the door, and the door's coupling to its guides and fixings, are able to interact without binding, bouncing or undue stress, which might otherwise prematurely wear mechanical components or interfere with the operator unit's ability to quickly and reliably detect the door meeting an obstruction.        
As discussed above, for economic and inventory reasons it is desirable to provide an operator unit which can be used with as many different types and sizes of garage doors as possible, and preferably without requiring complex customisation prior to installation. The operator unit drive speed therefore needs to be capable of adjustment by the technician performing the installation. Such adjustment has conventionally been achieved either mechanically or electronically.
Mechanical speed adjustment often involves changing the size of the drive sprocket or gearing so that the resulting travel speed is modified, and examples of such solutions are described in U.S. Pat. Nos. 4,794,731 and 5,137,500. This type of solution requires partial disassembly of the operator unit, which can involve significant work and time on the part of the installer. Due to the physical limitation on the size of the sprockets available, and the economic limitations restricting the number of sprockets provided as part of the operator unit kit, this approach is generally inconvenient and provides only a limited range of possible speed adjustment. Another mechanical speed adjustment is proposed in Australian Patent Application No. AU2008264221. This concept uses a ‘piggy-back’ arrangement of a selected number of interengaged reduction gearbox units, to adapt the drive from a motor to suit different closures. Again, such an arrangement is generally inconvenient, particularly when limited space is available.
Another disadvantage of this form of speed adjustment is that the adjustment applies to both open and close directions of travel, with independent adjustment not being possible. It is often desirable to have a relatively slow closing speed, so that the operator unit's controller is able to detect obstructions before damage can occur (the slower the door is closing, the more time is available to prevent damage), and a faster opening speed, so that the opening travel can complete in a relatively short time. Furthermore, changing the drive sprocket alters the operator unit's load capability, travel limit settings and obstruction detection sensitivity, and the prior art provides no ready way to make allowance for these changes.
Electronic speed adjustment on the other hand does not generally require disassembly of the operator unit. Previously, electronic speed adjustment has been possible by special in-situ programming of the operator unit controller. This involves the use of hand held programming consoles which are connected to the operator unit and are used to modify the aspect of the programming of the controller which determines motor speed, for example, selecting the drive voltage to be applied to the motor. This method requires the installation technician to switch between programmer and operator unit consoles, or to switch between limit setup mode and speed adjustment mode, and this can be a significant inconvenience at installation, and particularly a safety concern when access to the operator requires the use of a ladder.
The result of such conventional approaches is that installation times are extended, speed setting are not adjusted to optimum values, or speed setting is omitted altogether due to complexity or due to the time required.